Overmolded lens over LED die

ABSTRACT

One or more LED dice are mounted on a support structure. The support structure may be a submount with the LED dice already electrically connected to leads on the submount. A mold has indentations in it corresponding to the positions of the LED dice on the support structure. The indentations are filled with a liquid optically transparent material, such as silicone, which when cured forms a lens material. The shape of the indentations will be the shape of the lens. The mold and the LED dice/support structure are brought together so that each LED die resides within the liquid silicone in an associated indentation. The mold is then heated to cure (harden) the silicone. The mold and the support structure are then separated, leaving a complete silicone lens over each LED die. This over molding process may be repeated with different molds to create concentric shells of lenses. Each concentric lens may have a different property, such as containing a phosphor, providing a special radiation pattern, having a different hardness value, or curable by a different technique (e.g., UV vs. heat).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. application Ser. No. 10/990,208,filed Nov. 15, 2004, by Grigoriy Basin et al., entitled “Molded LensOver LED Die.”

FIELD OF THE INVENTION

This invention relates to light emitting diodes (LEDs) and, inparticular, to a technique for forming a lens over an LED die.

BACKGROUND

LED dies typically emit light in a lambertian pattern. It is common touse a lens over the LED die to narrow the beam or to make aside-emission pattern. A common type of lens for a surface mounted LEDis preformed molded plastic, which is bonded to a package in which theLED die is mounted. One such lens is shown in U.S. Pat. No. 6,274,924,assigned to Lumileds Lighting and incorporated herein by reference.

SUMMARY

A technique for forming a lens for surface mounted LEDs is describedherein.

One or more LED dice are mounted on a support structure. The supportstructure may be a ceramic substrate, a silicon substrate, or other typeof support structure with the LED dice electrically connected to metalpads on the support structure. The support structure may be a submount,which is mounted on a circuit board or a heat sink in a package.

A mold has indentations in it corresponding to the positions of the LEDdice on the support structure. The indentations are filled with aliquid, optically transparent material, such as silicone, which whencured forms a hardened lens material. The shape of the indentations willbe the shape of the lens. The mold and the LED dice/support structureare brought together so that each LED die resides within the liquid lensmaterial in an associated indentation.

The mold is then heated to cure (harden) the lens material. The mold andthe support structure are then separated, leaving a complete lens overeach LED die. This general process will be referred to as overmolding.

The overmolding process may be repeated with different molds to createconcentric or overlapping shells of lenses. Each lens may have adifferent property, such as containing a phosphor, being a differentmaterial, providing a different radiation pattern, having a differenthardness value, having a different index of refraction, or curable by adifferent technique (e.g., UV vs. heat).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of four LED dice mounted on a support structure,such as a submount, and a mold for forming a lens around each LED die.

FIG. 2 is a side view of the LED dice being inserted into indentationsin the mold filled with a liquid lens material.

FIG. 3 is a side view of the LED dice removed from the mold after theliquid has been cured, resulting in a lens encapsulating each LED die.

FIG. 4 is a perspective view of an array of LED dice on a submount orcircuit board with a molded lens formed over each LED die.

FIG. 5 is a close-up side view of a flip-chip LED die mounted on asubmount, which is, in turn, mounted on a circuit board, and where amolded lens is formed over the LED die.

FIG. 6 is a close-up side view of a non-flip-chip LED die mounted on asubmount, which is, in turn, mounted on a circuit board, where wireselectrically connect n and p metal on the LED die to leads on thecircuit board, and where a molded lens is formed over the LED die.

FIGS. 7, 8, 9, 10, and 11 are cross-sectional views of an LED die withdifferent lenses formed over it.

FIG. 12 is a cross-sectional view of a side-emitting lens molded ontothe LED die using the inventive techniques.

FIG. 13 is a cross-sectional view of a collimating lens molded onto theLED die using the inventive techniques.

FIG. 14 is a cross-sectional view of a preformed side-emitting lensaffixed over a lambertian lens that has been molded onto the LED dieusing the inventive techniques.

FIG. 15 is a cross-sectional view of a backlight for a liquid crystaldisplay or other type of display using the LED and side-emitting lens ofFIG. 14.

FIG. 16 is a perspective view of a cell phone with a camera that uses asa flash an LED with a molded lens.

FIGS. 17 and 18 are cross-sectional views of two types of molded lenses.All lenses shown are symmetrical about the center axis, although theinvention may apply to non-symmetrical lenses as well.

FIGS. 19-22 illustrate surface features on an inner lens or an outershell lens for obtaining a desired emission pattern.

FIG. 23 illustrates the use of a high domed lens for a collimatedemission pattern.

FIGS. 24 and 25 illustrate the use of a hard outer lens and a soft innerlens to limit the stress on a wire bond.

FIGS. 26-28 illustrate the use of an outer lens formed on various typesof inner or intermediate lenses for a side-emitting pattern.

FIG. 29 illustrates another side-emitting molded lens.

FIG. 30 illustrates the use of molded shells, each containing adifferent phosphor.

FIG. 31 illustrates forming a mold portion on the support substrate forforming a molded lens.

FIG. 32 illustrates depositing a metal reflector over a portion of thelens for achieving a desired emission pattern.

FIG. 33 is a side view of a liquid crystal display using LEDs withside-emitting lenses in a backlight.

FIG. 34 is a side view of a rear projection TV using LEDs withcollimating lenses as a RGB light source.

DETAILED DESCRIPTION

As a preliminary matter, a conventional LED is formed on a growthsubstrate. In the example used, the LED is a GaN-based LED, such as anAlInGaN LED, for producing blue or UV light. Typically, a relativelythick n-type GaN layer is grown on a sapphire growth substrate usingconventional techniques. The relatively thick GaN layer typicallyincludes a low temperature nucleation layer and one or more additionallayers so as to provide a low-defect lattice structure for the n-typecladding layer and active layer. One or more n-type cladding layers arethen formed over the thick n-type layer, followed by an active layer,one or more p-type cladding layers, and a p-type contact layer (formetallization).

Various techniques are used to gain electrical access to the n-layers.In a flip-chip example, portions of the p-layers and active layer areetched away to expose an n-layer for metallization. In this way the pcontact and n contact are on the same side of the chip and can bedirectly electrically attached to the package (or submount) contactpads. Current from the n-metal contact initially flows laterally throughthe n-layer. In contrast, in a vertical injection (non-flip-chip) LED,an n-contact is formed on one side of the chip, and a p-contact isformed on the other side of the chip. Electrical contact to one of the por n-contacts is typically made with a wire or a metal bridge, and theother contact is directly bonded to a package (or submount) contact pad.A flip-chip LED is used in the examples of FIGS. 1-3 for simplicity.

Examples of forming LEDs are described in U.S. Pat. Nos. 6,649,440 and6,274,399, both assigned to Lumileds Lighting and incorporated byreference.

Optionally, a conductive substrate is bonded to the LED layers(typically to the p-layers) and the sapphire substrate is removed. Oneor more LED dice may be bonded to a submount, with the conductivesubstrate directly bonded to the submount, to be described in greaterdetail with respect to FIGS. 5 and 6. One or more submounts may bebonded to a printed circuit board, which contains metal leads forconnection to other LEDs or to a power supply. The circuit board mayinterconnect various LEDs in series and/or parallel.

The particular LEDs formed and whether or not they are mounted on asubmount is not important for purposes of understanding the invention.

FIG. 1 is a side view of four LED dice 10 mounted on a support structure12. The support structure may be a submount (e.g., ceramic or siliconwith metal leads), a metal heat sink, a printed circuit board, or anyother structure. In the present example, the support structure 12 is aceramic submount with metal pads/leads.

A mold 14 has indentations 16 corresponding to the desired shape of alens over each LED die 10. Mold 14 is preferably formed of a metal. Avery thin non-stick film 18, having the general shape of mold 14, isplaced over mold 14. Film 18 is of a well known conventional materialthat prevents the sticking of silicone to metal.

Film 18 is not needed if the lens material does not stick to the mold.This may be accomplished by using a non-stick mold coating, using anon-stick mold material, or using a mold process that results in anon-stick interface. Such processes may involve selecting certainprocess temperatures to obtain the minimum stick. By not using film 18,more complex lenses can be formed.

In FIG. 2, the mold indentions 16 have been filled with a heat-curableliquid lens material 20. The lens material 20 may be any suitableoptically transparent material such as silicone, an epoxy, or a hybridsilicone/epoxy. A hybrid may be used to achieve a matching coefficientof thermal expansion (CTE). Silicone and epoxy have a sufficiently highindex of refraction (greater than 1.4) to greatly improve the lightextraction from an AlInGaN or AlInGaP LED as well as act as a lens. Onetype of silicone has an index of refraction of 1.76.

A vacuum seal is created between the periphery of the support structure12 and mold 14, and the two pieces are pressed against each other sothat each LED die 10 is inserted into the liquid lens material 20 andthe lens material 20 is under compression.

The mold is then heated to about 150 degrees centigrade (or othersuitable temperature) for a time to harden the lens material 20.

The support structure 12 is then separated from mold 14. Film 18 causesthe resulting hardened lens to be easily released from mold 14. Film 18is then removed.

In another embodiment, the LED dice 10 in FIG. 1 may be first coveredwith a material, such as silicone or phosphor particles in a binder. Themold indentations 16 are filled with another material. When the dice arethen placed in the mold, the mold material is shaped over the coveringmaterial.

FIG. 3 illustrates the resulting structure with a molded lens 22 overeach LED die 10. In one embodiment, the molded lens is between 1 mm and5 mm in diameter. The lens 22 may be any size or shape. FIG. 4 is aperspective view of a resulting structure where the support structure 12supports an array of LED dice, each having a molded lens 22. The moldused would have a corresponding array of indentations. If the supportstructure 12 were a ceramic or silicon submount, each LED (with itsunderlying submount portion) can be separated by sawing or breaking thesubmount 12 to form individual LED dice. Alternatively, the supportstructure 12 may be separated/diced to support subgroups of LEDs or maybe used without being separated/diced.

The lens 22 not only improves the light extraction from the LED die andrefracts the light to create a desired emission pattern, but the lensalso encapsulates the LED die to protect the die from contaminants, addmechanical strength, and protect any wire bonds.

FIG. 5 is a simplified close-up view of one embodiment of a singleflip-chip LED die on a submount 24 formed of any suitable material, suchas a ceramic or silicon. In one embodiment, submount 24 acted as thesupport structure 12 in FIGS. 1-4, and the die/submount of FIG. 5 wasseparated from the structure of FIG. 4 by sawing. The LED die 10 of FIG.5 has a bottom p-contact layer 26, a p-metal contact 27, p-type layers28, a light emitting active layer 30, n-type layers 32, and an n-metalcontact 31 contacting the n-type layers 32. Metal pads on submount 24are directly metal-bonded to contacts 27 and 31. Vias through submount24 terminate in metal pads on the bottom surface of submount 24, whichare bonded to the metal leads 40 and 44 on a circuit board 45. The metalleads 40 and 44 are connected to other LEDs or to a power supply.Circuit board 45 may be a metal plate (e.g., aluminum) with the metalleads 40 and 44 overlying an insulating layer. The molded lens 22,formed using the technique of FIGS. 1-3, encapsulates the LED die 10.

The LED die 10 in FIG. 5 may also be a non-flip-chip die, with a wireconnecting the top n-layers 32 to a metal pad on the submount 24. Thelens 22 may encapsulate the wire.

In one embodiment, the circuit board 45 itself may be the supportstructure 12 of FIGS. 1-3. Such an embodiment is shown in FIG. 6. FIG. 6is a simplified close-up view of a non-flip-chip LED die 10 having a topn-metal contact 34 connected to a metal lead 40 on circuit board 45 by awire 38. The LED die 10 is mounted on a submount 36, which in theexample of FIG. 6 is a metal slab. A wire 42 electrically connects thep-layers 26/28 to a metal lead 44 on circuit board 45. The lens 22 isshown completely encapsulating the wires and submount 36; however, inother embodiments the entire submount or the entire wire need not beencapsulated.

A common prior art encapsulation method is to spin on a protectivecoating. However, that encapsulation process is inappropriate for addinga phosphor coating to the LED die since the thickness of the encapsulantover the LED die is uneven. Also, such encapsulation methods do not forma lens. A common technique for providing a phosphor over the LED die isto fill a reflective cup surrounding the LED die with asilicone/phosphor composition. However, that technique forms a phosphorlayer with varying thicknesses and does not form a suitable lens. If alens is desired, additional processes still have to create a plasticmolded lens and affix it over the LED die.

FIGS. 7-11 illustrate various lenses that may be formed using theabove-described techniques.

FIG. 7 illustrates an LED die 10 that has been coated with a phosphor 60using any suitable method. One such method is by electrophoresis,described in U.S. Pat. No. 6,576,488, assigned to Lumileds Lighting andincorporated herein by reference. Suitable phosphors are well known. Alens 22 is formed using the techniques described above. The phosphor 60is energized by the LED emission (e.g., blue or UV light) and emitslight of a different wavelength, such as green, yellow, or red. Thephosphor emission alone or in conjunction with the LED emission mayproduce white light.

Processes for coating an LED with a phosphor are time-consuming. Toeliminate the process for coating the LED die with a phosphor, thephosphor powder may be mixed with the liquid silicone so as to becomeembedded in the lens 62, shown in FIG. 8.

As shown in FIG. 9, to provide a carefully controlled thickness ofphosphor material over the LED die, an inner lens 64 is formed using theabove-described techniques, and a separate molding step (using a moldwith deeper and wider indentations) is used to form an outerphosphor/silicone shell 66 of any thickness directly over the inner lens64.

FIG. 10 illustrates an outer lens 68 that may be formed over thephosphor/silicone shell 66 using another mold to further shape the beam.

FIG. 11 illustrates shells 70, 72, and 74 of red, green, andblue-emission phosphors, respectively, overlying clear silicone shells76, 78, and 80. In this case, LED die 10 emits UV light, and thecombination of the red, green, and blue emissions produces a whitelight. All shells are produced with the above-described methods.

Many other shapes of lenses can be formed using the molding techniquedescribed above. FIG. 12 is a cross-sectional view of LED 10, submount24, and a molded side-emitting lens 84. In one embodiment, lens 84 isformed of a very flexible material, such as silicone, which flexes as itis removed from the mold. When the lens is not a simple shape, therelease film 18 (FIG. 1) will typically not be used.

FIG. 13 is a cross-sectional view of LED 10, submount 24, and a moldedcollimating lens 86. The lens 86 can be produced using a deformable moldor by using a soft lens material that compresses when being pulled fromthe mold and expands to its molded shape after being released from themold.

FIG. 14 illustrates how a preformed lens 88 can be affixed over a moldedlambertian lens 22. In the example of FIG. 14, lens 22 is formed in thepreviously described manner. Lens 22 serves to encapsulate and protectLED 10 from contaminants. A preformed side-emitting lens 88 is thenaffixed over lens 22 using a UV curable adhesive or a mechanical clamp.This lens-forming technique has advantages over conventional techniques.In a conventional technique, a preformed lens (e.g., a side emittinglens) is adhesively affixed over the LED die, and any gaps are filled inby injecting silicone. The conventional process is difficult to performdue to, among other reasons, carefully positioning the separateddie/submount for the lens placement and gap-filling steps. Using theinventive technique of FIG. 14, a large array of LEDs (FIG. 4) can beencapsulated simultaneously by forming a molded lens over each. Then, apreformed lens 88 can be affixed over each molded lens 22 while the LEDsare still in the array (FIG. 4) or after being separated.

Additionally, the molded lens can be made very small (e.g., 1-2 mmdiameter), unlike a conventional lens. Thus, a very small, fullyencapsulated LED can be formed. Such LEDs can be made to have a very lowprofile, which is beneficial for certain applications.

FIG. 14 also shows a circuit board 45 on which submount 24 is mounted.This circuit board 45 may have mounted on it an array of LEDs/submounts24.

FIG. 15 is a cross-sectional view of a backlight for a liquid crystaldisplay (LCD) or other display that uses a backlight. Common uses arefor televisions, monitors, cellular phones, etc. The LEDs may be red,green, and blue to create white light. The LEDs form a two-dimensionalarray. In the example shown, each LED structure is that shown in FIG.14, but any suitable lens may be used. The bottom and sidewalls 90 ofthe backlight box are preferably coated with a whitereflectively-diffusing material. Directly above each LED is a whitediffuser dot 92 to prevent spots of light from being emitted by thebacklight directly above each LED. The dots 92 are supported by atransparent or diffusing PMMA sheet 94. The light emitted by theside-emitting lenses 88 is mixed in the lower portion of the backlight,then further mixed in the upper portion of the backlight before exitingthe upper diffuser 96. Linear arrays of LEDs may be mounted on narrowcircuits boards 45.

FIG. 16 illustrates an LED 10 with a molded lens 22 being used as aflash in a camera. The camera in FIG. 16 is part of a cellular telephone98. The cellular telephone 98 includes a color screen 100 (which mayhave a backlight using the LEDs described herein) and a keypad 102.

As discussed with respect to FIG. 10, an outer lens may be formed overthe inner shell to further shape the beam. Different shell materials maybe used, depending on the requirements of the various shells. FIGS.17-30 illustrate examples of various lenses and materials that may beused in conjunction with the overmolding process.

FIGS. 17 and 18 illustrate two shapes of molded lenses for an innershell formed using the molding techniques described above. Many LEDs 10may be mounted on the same support structure 12. The support structure12 may be a ceramic or silicon submount with metal traces and contactpads, as previously described. Any number of LEDs may be mounted on thesame support structure 12, and all LEDs on the same support structure 12would typically be processed in an identical manner, although notnecessarily. For example, if the support structure were large and thelight pattern for the entire LED array were specified, each LED lens maydiffer to provide the specified overall light pattern.

An underfill material may be injected to fill any gap between the bottomof the LED die 10 and the support substrate 12 to prevent any air gapsunder the LED and to improve heat conduction, among other things.

FIG. 17 has been described above with respect to FIGS. 3-6, where theinner molded lens 22 is generally hemispherical for a lambertianradiation pattern. The inner molded lens 106 in FIG. 18 is generallyrectangular with rounded edges. Depending on the radiation pattern to beprovided by an outer lens, one of the inner molded lenses 22 or 106 maybe more suitable. Other shapes of inner molded lenses may also besuitable. The top down view of each lens will generally be circular.

FIG. 19 illustrates the structure of FIG. 18 with the lens outer surfacehaving a pattern that refracts light to achieve a desired radiationpattern. The outer surface pattern may be directly formed in the innermolded lens (by the mold itself), or the outer surface pattern may beformed in an outer lens that is overmolded onto the inner molded lens oris affixed to it by an adhesive (e.g., silicone, epoxy, etc.). Pattern108 is a diffraction grating, while pattern 110 uses binary steps torefract the light. In the examples, the pattern forms a generallyside-emitting lens with the radiation pattern shown in FIG. 20. In FIG.20, the peak intensity occurs within 50-80 degrees and is significantlygreater than the intensity at 0 degrees.

The requirements for the inner lens are generally different from therequirements for the outer lens. For example, the inner lens should havegood adhesion to the support structure, not yellow or become more opaqueover time, have a high index of refraction (greater than 1.4), not breakor stress any wires to the LED, withstand the high LED temperatures, andhave a compatible thermal coefficient. The inner lens should benon-rigid (e.g., silicone) to not provide stress on the LED or anywires. In contrast, the outer lens material generally only needs to beable to be patterned with the desired pattern and adhere to the innerlens. The outer lens may overmolded or may be preformed and adhesivelyaffixed to the inner lens. The material for the outer lens may be UVcurable, while the material for the inner lens may be thermally cured.Thermal curing takes longer than UV curing.

Generally, the range of hardness for the inner lens material is Shore 005-90, while the range of hardness for the outer shell(s) is Shore A 30or more.

FIG. 21 illustrates a Fresnel lens pattern 112 formed on the outersurface of the lens for creating a generally side-emitting light patternsimilar to that of FIG. 20. The outer surface may be the outer surfaceof the inner molded lens or the outer surface of an outer shell, asdescribed with respect to FIG. 19. This applies to all patternsdescribed herein.

FIG. 22 illustrates pyramid 114 or cone shaped 116 patterns on the outerlens surface to create a collimating light pattern or another lightpattern.

FIG. 23 illustrates a high dome outer lens 118 for creating acollimating pattern.

The surface patterns of FIGS. 19 and 21-23 may be configured (e.g., bychanging the surface angles) to create any light pattern. Holographicstructures, TIR, and other patterns may be formed. Collimating lightpatterns are typically used for rear projection TVs, while side-emittinglight patterns are typically used for backlighting LCD screens.

FIG. 24 illustrates the use of a soft (e.g, Shore XX) material, such asa silicone gel, as the inner molded lens 124 so as to not stress thewire 126 bonded to the LED 10. The gel is typically UV cured. The outerlens 128 may be molded or preformed and affixed with an adhesive. Theouter lens 128 will typically be much harder for durability, resistanceto particles, etc. The outer lens 128 may be silicone, epoxy-silicone,epoxy, silicone elastomers, hard rubber, other polymers, or othermaterial. The outer lens may be UV or thermally cured.

FIG. 25 is similar to FIG. 24 but with a different shaped inner moldedlens 129 (like FIG. 18) for a different emission pattern or a lowerprofile. Lens 129 may be a soft silicone gel. The outer lens 130 willfurther shape the emission pattern and protect the soft inner lens 129.

The LEDs in all figures may be flip-chips or wire bonded types.

FIG. 26 illustrates an LED structure with a soft inner molded lens 132,having the properties needed for the inner lens, a hard intermediateshell 134 to act as an interface layer and for structural stability, andan outer lens 136 for creating a side-emitting light pattern. The outerlens 136 may be soft to facilitate the molding process. Alternatively,the outer lens 136 may be preformed and adhesively affixed to theintermediate shell 134. The use of the intermediate shell 134 makes thechoice of the outer lens material essentially independent of the innerlens material.

FIG. 27 illustrates how the outer lens 138 may be formed on any portionof the intermediate shell 134 or inner lens 132.

FIG. 28 illustrates the formation of the outer lens 142 directly on theinner lens 144 material.

FIG. 29 illustrates another shape of side-emitting lens 145 molded overan inner lens 132. Lens 145 may be directly molded over LED die 10without any inner lens.

FIG. 30 illustrates an LED where each shell 146, 147, and 148 contains adifferent phosphor material, such as a red-emitting phosphor, agreen-emitting phosphor, and a blue-emitting phosphor. The LED die 10may emit UV. The gaps between phosphor particles allow the UV to passthrough an inner shell to energize the phosphor in an outer shell.Alternatively, only red and green phosphor shells are used, and the LEDdie 10 emits blue light. The combination of red, green, and blue lightcreate white light. The thickness of the shells, the density of thephosphor particles, and the order of the phosphor colors, among otherthings, can be adjusted to obtain the desired light. Any shape of lensesmay be used.

FIG. 31 illustrates the use of a mold pattern 149 on the supportstructure 12 itself. A high index material (e.g., a polymer) or areflective material (e.g., aluminum or silver) is formed by eithermolding the pattern on the support structure 12, using a method similarto the method shown in FIG. 1, or using a metallization process, orusing another suitable process. The mold pattern 149 is then used as amold for another material forming a lens 150. In one embodiment, thelens 150 material is a liquid (e.g., silicone) that is deposited in themold formed on the support structure 12, then cured. The surface maythen be planarized. The resulting lens collimates the light byreflecting/refracting the light impinging on the walls like a reflectorcup.

FIG. 32 illustrates a molded lens 22 with metal 151 sputtered around itsside to reflect light emitted by the LED 10. The reflected light will bescattered by the LED 10 and be eventually emitted through the topopening. The metal 151 may be any reflective material such as aluminumor silver. The metal may instead be sputtered on the top of the lens 22to create a side-emission pattern. The lens 22 may be made any shape tocreate the desired light emission pattern.

FIG. 33 is a side view of a liquid crystal display (LCD) 152 with an LCDscreen 154, having controllable RGB pixels, a diffuser 156, and abacklight 158 for mixing light from red, green, and blue LEDs 160 tocreate white light. The backlight 158 is a diffusively reflective box.The LEDs 160 have side-emitting lenses made using any of theabove-described techniques.

FIG. 34 is a side view of a rear projection television 162 with a frontlens 164 for brightening the image within a specified viewing angle, aset of red, green, and blue LEDs 166, modulator/optics 170 formodulating and focusing the RGB light to produce a color TV image, and areflector 172. The modulator may be an array of controllable mirrors, anLCD panel, or any other suitable device. The LEDs 166 have collimatinglenses made using any of the above-described techniques.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects and, therefore, the appended claims areto encompass within their scope all such changes and modifications asfall within the true spirit and scope of this invention.

1. A method for forming a lens over a light emitting diode (LED) diecomprising: providing an LED die attached to a support structure; andmolding a first lens of a first material over the die while attached tothe support structure.
 2. The method of claim 1 wherein molding thefirst lens further comprises curing the first material using a thermalor UV cure.
 3. The method of claim 1 wherein molding the first lenscomprises: filling a first indentation in a first mold with a first lensmaterial; bringing the first mold and the support structure together sothat the LED die is within the first lens material; curing the liquidfirst lens material; and removing the support structure from the firstmold so that a first lens formed from the cured first lens materialoverlies the LED die.
 4. The method of claim 1 wherein the supportstructure comprises a submount having metal leads in electrical contactwith metal contacts on the LED die.
 5. The method of claim 1 wherein theLED die is one of a plurality of LED dice affixed to the supportstructure.
 6. The method of claim 1 wherein the first lens is formed indirect contact with the LED die.
 7. The method of claim 1 whereinmolding the first lens further comprises molding a pattern into asurface of the first lens for affecting an emitted light pattern.
 8. Themethod of 7 wherein the pattern comprises a Fresnel lens, a diffractiongrating, a binary pattern, pyramids, or cones.
 9. The method of claim 1further comprising providing an optical element affixed to the firstlens to obtain a desired light pattern.
 10. The method of claim 9wherein the optical element comprises a second lens of a second materialdifferent from the first material.
 11. The method of claim 9 wherein theoptical element comprises a second lens of a second material differentfrom the first material, and wherein providing the optical elementcomprises: molding the second lens over the first lens; and curing thesecond material.
 12. The method of claim 9 wherein the optical elementcomprises a second lens of a second material different from the firstmaterial, and wherein providing the optical element comprises: moldingthe second lens over the first lens, the second lens having a surfacepattern comprising a Fresnel lens, a diffraction gradient, a binarypattern, pyramids, or cones.
 13. The method of claim 9 wherein theoptical element comprises a second lens of a second material harder thanthe first material.
 14. The method of claim 10 wherein a range ofhardness of the first lens is Shore 00 5-90, and the hardness of thesecond lens is greater than Shore A
 30. 15. The method of claim 9wherein providing the optical element comprises depositing a reflectivematerial on an outer surface of the first lens.
 16. The method of claim9 wherein the optical element is a collimating lens.
 17. The method ofclaim 9 wherein the optical element is a side-emitting lens.
 18. Themethod of claim 9 wherein the optical element comprises a second lens ofa second material different from the first material, wherein the firstmaterial and the second material comprise silicone, epoxy, or asilicone/epoxy hybrid.
 19. The method of claim 9 wherein providing theoptical element comprises: providing a second mold having a secondindentation filled with a second lens material; bringing together thesecond mold and the support structure, having attached to it the LED diehaving the first lens, so that the first lens is within the second lensmaterial in the second indentation; curing the second lens material; andremoving the support structure from the second mold so that the secondlens material forms a first shell over the first lens.
 20. The method ofclaim 9 wherein providing the optical element comprises providing anoptical element directly on the first lens.
 21. The method of claim 9wherein the optical element comprises a second lens over the first lens,the first lens containing a first phosphor, and the second lenscontaining a second phosphor.
 22. The method of claim 21 wherein acombination of the LED light and the light emitted by the phosphorscreates white light.
 23. The method of claim 9 wherein the opticalelement comprises a second lens over the first lens, the method furthercomprising molding a third lens over the second lens, the first lenscontaining a first phosphor, the second lens containing a secondphosphor, and the third lens containing a third phosphor.
 24. A methodfor forming a lens over a light emitting diode (LED) die comprising:providing an LED die attached to a support structure; forming a mold onthe support structure; and molding a first lens of a first material overthe die while attached to the support structure, using the mold on thesupport structure to define the shape of the first lens.
 25. The methodof claim 24 wherein molding the first lens comprises depositing a lensmaterial in the mold on the support structure and then curing the lensmaterial.
 26. A light emitting device comprising: a light emitting diode(LED) die attached to a support structure; and a first lens molded overthe LED die and encapsulating the LED die.
 27. The device of claim 26further comprising an optical element affixed to the first lens toobtain a desired light pattern.
 28. The device of claim 27 wherein theoptical element comprises a second lens of a second material differentfrom the first material.
 29. The device of claim 28 wherein the secondlens is molded over the first lens.
 30. The device of claim 28 whereinthe second lens has a pattern molded into its surface for affecting anemitted light pattern.
 31. The device of claim 30 wherein the patterncomprises a Fresnel lens, a diffraction grating, a binary pattern,pyramids, or cones.
 32. The device of claim 26 wherein the first lenshas a pattern molded into its surface for affecting an emitted lightpattern.
 33. The device of claim 32 wherein the pattern comprises aFresnel lens, a diffraction grating, a binary pattern, pyramids, orcones.
 34. The device of claim 26 wherein the LED die is one of aplurality of LED dice affixed to the support structure.
 35. The deviceof claim 26 further comprising a backlight for a liquid crystal display,the backlight incorporating the LED and first lens.
 36. The device ofclaim 26 further comprising a rear projection television, the televisionincorporating the LED and first lens.